Here are some of the subjects that books for young adults tackled in the past year or so: School shootings, terrorism, post-traumatic stress disorder, homelessness, sex, discrimination, substance abuse, death and grieving.

That may make some of us well past adolescence want to go home to read “A Girl of the Limberlost,” Gene Stratton-Porter’s sympathetic 1909 novel about a plucky, wholesome girl. Who, um, was bullied and neglected by her widowed mother, and earned her nickname by going into the daunting Limberlost forest to find biological specimens to sell because she was so poor.

“These subjects have always been out there,” observed Beverly Horowitz, vice president and publisher of Delacorte Press, a prominent fixture in the world of young-adult literature.

As the young adult fiction genre expands, more books deliberately are tackling longtime issues — sex, drug abuse, poverty — along with subjects straight from news headlines. Last year’s “Get Real: Telling It Like It Is” campaign by Sourcebooks Fire promoted books on topics much scarier than werewolves and vampires (another popular YA trend).

“When teenagers read about suicide or drug abuse, we, as adults, want to know why they’re reading about those things,” said Jay Asher, author of the enormously popular ” Thirteen Reasons Why,” a suicidal girl’s posthumous message to classmates she blames for her death. Asher is a keynote speaker at the sold-out Colorado Teen Literature Conference on Saturday.

“The important thing is that it’s important to talk about these issues. ‘Thirteen Reasons Why’ would not have been as successful if, as a society, we talked more openly and honestly about these things.”

“Thirteen Reasons Why” resonated dramatically with adolescent readers in the U.S. and abroad. So far, it’s been sold and published in more than 30 countries, “particularly in cultures where people don’t talk about death,” Asher said.

“Adults worry that my book glorifies suicide. But what I hear from readers, over and over, is ‘Someone understands me.’ Just this morning, I got an e-mail from a girl who attempted suicide and found my book after she was hospitalized. She wrote to tell me she wasn’t getting an honest discussion from people around her. Fiction is a safe way for kids to explore these issues.”

Few adolescents are untouched by war. They have friends, siblings, relatives, and neighbors who have served in Iraq or Afghanistan. Their churches, synagogues and mosques host military funerals, and sometimes funerals for those who’ve suffered collateral damage resulting from post-traumatic stress disorder.

How does a brother handle the news that his dead war-hero brother left mementos for a boyfriend, not a girlfriend?

Should a presumed girlfriend maintain the fiction at home for the sake of the gay enlisted soldier who definitely is not her boyfriend?

How can life go on after someone you love dies in a war he was beginning to doubt?

Another subject, even closer to home: guns in schools. Beck McDowell’s “This is NOT a Drill”is a taut, terrifyingly plausible story about a deranged man who holds a school classroom hostage at gunpoint. It was published last October, two months before the Newtown, Conn., school massacre.

“Kids are dealing with a world that has changed,” Horowitz says.

“People are trying to make sense of what’s going on in the world. These books, in their way, show different stages and different reactions of people of different ages. Some of the best kinds of YA writing include adults who are as imperfect as the teens, or who are overwhelmed, or who make a mistake and acknowledge that. It is so important for young people — for educators, for parents — to see that you can’t make everything right. You wish you could. But you can’t deny that things happen.”

Actually, some people would like to deny that “things happen,” which is one reason Banned Books Week has become more than an annual event. Most recently, “Persepolis,” a graphic novel about a young woman coming of age in revolutionary Iran, was banned in Chicago public school seventh-grade classrooms. Banning books, says Carol A. Edwards, who co-manages children’s and family services for the Denver Public Library, is not going to help children navigate an increasingly complex society.

“My take on the YA books is that kids read books in order to understand the world around them,” Edwards said.

“If you don’t personally experience death or acne or being unpopular, but want to understand it, then reading about those things is one way to experience it. Bibliotherapy may not be useful for the person who’s already going through grief — for example, having survived Iraq and come back home — but I think it can help kids understand what that person’s been through.”